Pelargonium Graveolens) on Leaf Positions for Commercial Exploitation

African Journal of Agricultural Research Vol. 5 (15), pp. 2077-2079, 4 August, 2010 Available online at http://www.academicjournals.org/AJAR DOI: 10.5897/AJAR09.189 ISSN 1991-637X ©2010 Academic Journals Short Communication Value addition of essential monoterpene oil(s) in Geranium (Pelargonium graveolens) on leaf positions for commercial exploitation A. Misra* and N. K. Srivastava Central Institute of Medicinal and Aromatic Plants, P.O.CIMAP, Kukrail Picnic Spot Road Lucknow – 226015, India. Accepted 9 July, 2010 While culturing geranium in controled glasshouse condition in sand culture techniques for maximum essential monoterpene oil(s), it was found that (0.21%) in young developed 4th position leaf. At 4th position of leaf, net photosynthetic rate, contents of chlorophyll and essential monoterpene oil(s) were affected. The maximum peroxidase activity was obtained at 4th position leaf with the production of biomolecule geraniol. The maximum of monoterpene oil(s) was found at 4th level. However, the relative contents of citronellol, geraniol, linalool, and nerol varied at different leaf positions. As a result of different leaf positions, the contents of Fe, Mn, Zn, and Cu were smaller in shoots of Geranium. Their maximum contents were observed at 4th positions. Thus the added value of essential monoterpene oil(s) seems for commercial exploitation at large scales to be for the collection of leaf position at 4th level and for better quality of total essential oil of Geranium. Key words: Geranium (Pelargonium graveolens L.), chlorophyll, Cu, dry mass, Fe, leaf area, Mn, net photosynthetic rate, plant height, saccharides, Zn. INTRODUCTION Geranium, Pelargonium graveolens L. Her. ex Ait. metal component of various enzymes or as a functional, (synonym P. roseum Willd.) of the family Geraniaceae is structural, or regulatory cofactor, and is thus associated the only source of one of the most important essential with saccharide metabolism, photosynthesis, and protein monoterpene oil(s) called the oil of geranium. It is com- synthesis (Marschner, 1086). Zn-deficiency reduces plant monly known as rose geranium. It is distinctly different growth and inhibits photosynthesis in many plants from the horticultural geranium, which are basically including forest trees (Dell and Wilson, 1985), fiber crops ornamental and have no commercial usage in perfumery (Ohki, 1976), rice (Ajay and Rathore, 1985), and spinach industries (Douglas, 1969). P. graveolens widely grown (Randall and Bouma, 1973). Zn retards the activity of cultivars Algerian/uniton, Kelkar/Egyptin, and Bourbon/- carbon metabolism enzymes such as carbonic anhydrase Reunion (Rajeshwar and Bhatacharya, 1992) are com- (Ohki, 1976, 1978), ribulose 1,5-bisphosphate monly cultivated in India. Steam distillation of shoot carboxylase/oxygenase and fructose-1,6-bisphosphate biomass of geranium yields geraniol and citronellol rich (Marschner, 1986). Zn, Se, and Cr are antioxidants sca- monoterpene oil(s), extensively used for perfuming soaps venging free radicals. Zn stimulates the removal of free- and cosmetics to which they impart a pronounced and radicals (Chakmak and Engles, 1999). lasting rose odour. It is also largely used in flavouring Essential oil biosynthesis in geranium is strongly tobacco products, toothpastes, ointments, and other influenced by Zn-acquisition and the stresses caused by pharmaceutical preparations. Zn on nutrition and growth. Zn is involved in carbon assi- Zn is an essential micronutrient that acts either as a milation, saccharide accumulation, free radical removal, anti-oxidant enzymes, carbon utilization in terpene biosynthesis, and the overall growth of the plants. The requirement of Zn for Japanese mint and its limitations *Corresponding author. E-mail: [email protected]. imposed on photosynthetic carbon metabolism and 2078 Afr. J. Agric. Res. translocation in relation to essential oil accumulation in at Zn0.250; at this Zn supply also the saccharide content mint were shown by Misra and Sharma (1991), whereas was the highest. Zn deficiency and Zn toxicity inhibited PN antioxidants enzymes for free radical quenching in in cotton (Ohki, 1976), peppermint (Randall and Bouma, geranium have not been fully documented. 1973), soybean (Ohki, 1978), and sweet mint (Misra et In the present paper we report on the role of Zn as a al., 2003). A decrease in Chl content represents a decline stimulant for quenching of free-radicals through Zn affect- in photochemical capacity of leaf at deficient Zn supply ted antioxidant enzyme activity. Simultaneously, photo- (Ohki, 1976). synthetic efficiency in terms of net photosynthetic rate Maxima of peroxidase activity were observed at Zn0.250. (PN), content of chlorophyll (Chl), leaf fresh and dry mass, The Zn deficient and toxic cultured plants revealed lesser leaf area, Zn content in plant shoot biomass and oil yield peroxidase activity with lesser peroxidase isoenzyme were also determined. band profiles. In Japanese mint similar report was given for Mn nutrition (1996). The maximum of monoterpene oil(s) was found at Zn0.250. However, relative contents of MATERIALS AND METHODS citronellol, geraniol, linalool, and nerol varied at different Zn treatments. As a result of different Zn supply the Plant tips (12.5 - 15.0 cm) with 3 - 4 leaves of P. graveolens of contents of Fe, Mn, Zn, and Cu were smaller in shoots of Bourbon genotype were obtained from the farm nursery of the CIMAP, Lucknow, India. Uniform cuttings were initially planted in geranium. Their maximum contents were observed at 3 10 000 cm earthen pots filled with purified silica sand (Agrawala Zn0.250. and Sharma, 1961) for the development of roots. After 15 days, Statistical analysis showed a positive significant asso- 3 rooted cuttings were transferred to 2 500 cm pots. The salts used ciation between Zn content in leaf and PN (γ = 0.924 ≤ in nutrient solution of Hoagland and Arnon (1952) were purified for p = 0.5%) and between P and content of saccharides Zn (Hewitt, 1952). The nutrient solution was used in the experiment N except Fe which was supplied as Fe-EDTA. Three pots each of Zn (γ = 0.879 ≤ p = 0.05%). However, Zn content in leaf was treatments ranging from 0.0 to 1.0 g(Zn) m-3 were maintained in negatively correlated with Chl a/b ratio. PN showed a controlled glasshouse condition at ambient temperature (30±5°C) positive significant association with leaf fresh mass (γ = and irradiance (800 – 1 000 μmol m-2 s-1). The nutrient solution in 791 ≤ p = 0.05 %), leaf dry mass (γ = 692 ≤ 0.05%), leaf each treatment was added at alternate days. With onset of area and total monoterpene oil(s) (γ = 0.721 ≤ p = 0.01). deficiency and toxicity (after 20 days), growth and detailed physio- A positive significant correlation was also observed logical and biochemical data characteristics were determined. PN was measured using a computerized portable photosynthesis between saccharides and total oil (γ = 0.695 ≤ p = system Li-COR 6000 (LiCOR, USA) (Misra and Srivastava, 1991). 0.01%). A quadratic trend was observed for all these Chl amount in 80% acetone extracts from 3rd leaf was determined characters which were comparable in +Zn than in plants spectrophotometrically on Pye Unicam PU8610 according to Arnon grown at Zn deficit or much higher Zn supply. (1949). Leaf fresh and shoot dry mass and area (area meter Li- We found that optimum supply of Zn is Zn0.250. 3000) were also recorded. For tissue element analysis 1 g dried Utilization of metabolites from primary photosynthetic leaf samples were digested with 1 M HCl at 60°C for 24 h. Aliquot samples of the clear digest were diluted with water (10 cm3) and process in secondary metabolism regulates monoterpene analyzed for Zn by atomic absorption spectrophotometer (Pye production (Gershezon and Croteau, 1991). Thus a close Unicam SP 2800) (Misra and Sharma, 1991). Antioxidant-reactive relation between photosynthesis, photorespiration, and peroxidase enzyme activity was estimated as described in Sharon terpenoid synthesis exists in essential monoterpene oil(s) et al. (1996). 2 g of freshly chopped leaves at 3rd position were bearing plants (Maffei and Codignola, 1990). Moreover, homogenized with 5 cm3 of 0.1 M phosphate buffer (pH 6.8). Each treatment was replicated 3 times and assayed by SDS-PAGE the actively growing leaves require a larger supply of an electrophoresis. antioxidants stimulator Zn, in association with greater Geranium oil was estimated by steam distillation of 100 g freshly supply of photosynthates. Since essential oil biosynthesis plucked leaves in an apparatus of Clevenger (1928). Geraniol, occurs in these rapidly growing leaves, the initial growth citronellol, and other associated oil contents were determined by period would require a still greater supply of photo- gas liquid chromatography (Perkin-Elmer model 3920 B). The synthates and energy. stainless steel column was packed with 10% carbowax (20 mesh) on Chromosorb WNAW. Injector and detector temperature were -1 maintained at 200°C. The flow of H2 was 0.47 cm s ; data processing for area % was done on a Hewlett- Packard integrator Conclusion model HP-33. Micronutrient contents of leaf tissue concentration suggest that third leaf position serves as a useful RESULTS AND DISCUSSION guidance in determining the convenience of a better clipping leaf, for better growth, productivity and essential The fresh and dry biomasses increased with increase in mono-terpene oil(s). The results of this study reveal that the supply of Zn (Table 1). Maximum fresh and dry the third leaves of the geranium plants which are actively biomass and leaf area were observed at Zn0.250. Plant growing leaves, require a larger supply of an antioxi- height was maximum at Zn0.500. Zn1.000 was toxic to all dants stimulator Zn, in association with greater supply of growth parameters. The Chl content increased up to photosynthates. Since essential oil biosynthesis occurs in Zn0.250 and then decreased. The maximum PN was found these, rapidly growing leaves, the initial growth period Misra and Srivastava 2079 Table 1.

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